The invention relates to a slide ring seal assembly, particularly a seal assembly for running gears. The seal assembly is composed of two, back-to-back arranged, cross-sectionally angled (L-shaped) slide rings whose axially extending legs form a seat for a stationary, cross-sectionally generally trapezoidal, resilient sealing body. The sealing bodies are secured against displacement by depressions provided in the outer upper surface of the legs.
Slide ring seal assemblies are used on shafts and axles and are inherently exposed to substantial soiling. Exemplary structures in which the slide ring seal assemblies may be used are drive axles of construction machinery or track-laying vehicles which are continuously exposed to sand, dust, mud and the like. Slide ring seal assemblies, particularly running gear seal assemblies where the slide rings have a cross-sectionally angled configuration often have cross-sectionally trapezoidal, spring-washer-shaped sealing bodies in which the slide rings are elastically supported. The annular sealing bodies which act as springs take over the function of the axial sealing pressure, the static seal between slide ring and seating bore and the frictional torque transmission. The axial force required for ensuring a seal is obtained by upsetting the elastic sealing body between the slide ring and its seating bore as the seal is stressed to assume its dimensions in the installed state. Particularly upon frictional torque transmission and distortion of the sealing body during installation or service, often malfunctioning and breakdown of the sealing properties are experienced.
A known slide ring seal assembly of the above-outlined type is described, for example, in German Patent No. 197 53 918. This patent describes a slide ring seal assembly having annular, cross-sectionally trapezoidal sealing bodies which are disposed between the axial legs of the slide rings and the seating bore. At the contact faces of the slide rings frictional torques appear which are transmitted by the sealing body to the housing. By virtue of the different distances from the axle center and thus from the null-line of the frictional torques, different forces in the supported surfaces of the sealing bodies appear. Thus, a relatively large force is obtained because of the short distance (leverage) to the outer upper face of the axial leg of the slide ring. A large distance (leverage) and thus a small force prevails between the null-line and the upper face of the seating bore. The frictional torques are conventionally transmitted by the surface pressure to the supporting surfaces of the sealing bodies. Due to the relatively high force effect on the outer upper surface of the axial leg of the slide ring, often the sealing body rotates with respect to the slide ring. Such a rotation causes a breakdown in the seal and thus renders the slide ring seal assembly defective.
To cure the above-outlined difficulty, U.S. Pat. No. 4,421,327 describes a slide ring seal assembly which includes a securing arrangement for preventing rotation of the sealing body. The forces on the upper surface of the axial leg of the slide ring are additionally taken up in a form-fitting manner by depressions provided therein. The sealing body thus can transmit significantly larger frictional torques. Such structures, however, involve the risk that the axially outer sealing body is twisted during dynamic stresses or even already in its installed state. As a result of such twist, the sealing body lifts off the radially outer upper surface of the slide ring leg, whereby a gap is formed between the slide ring leg and the sealing body. Dirt or lubricating oil may gain access to such a clearance. As an undesired result, the function of the slide ring seal assembly and the transmittable frictional torques are not optimal.